The stem and leaf plot is used to organize data. To construct it you have to "break" the data into steam and leaf. For the given data set, you have to separate both digits, the first digit will represent the steam and the second digit will represent the leaf.
First step, group the data acording to the first digit of the number:
Group 1:
60, 61, 62, 63, 63, 64, 64, 65, 66, 66, 66, 69
Group 2:
72, 72, 72, 74, 75
Group 3:
80, 82, 84, 86, 86, 87, 87, 89, 89
Group 4:
90, 93, 94, 98
The plot will have 4 stems 6, 7, 8, and 9, and the leaves will be the second digit of each observation that belongs to the group. They can be repeated as many times as the number itself is: